Flexible display device and method for manufacturing the same

ABSTRACT

Discussed is a flexible display device to reduce a width of a bezel. The flexible display device includes a substrate being formed of a flexible material, a plurality of gate lines and a plurality of data lines crossing each other, a plurality of pads formed in a pad area of a non-display area, a plurality of links formed in a link area of the non-display area a plurality of insulation films formed over the entire surface of the substrate, and a first bending hole formed in a bending area of the non-display area, the first bending hole passing through at least one of the insulation films disposed under the link, wherein the bending area is bent such that the pads are disposed on the lower surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a broadening Reissue application of U.S. Pat. No.9,293,485 issued on Mar. 22, 2016 (U.S. application Ser. No. 14/744,586filed Jun. 19, 2015), which is a Divisional of co-pending U.S.application Ser. No. 14/134,925 filed on Dec. 19, 2013 (now U.S. Pat.No. 9,082,667 issued Jul. 14, 2015), which claims the benefit of KoreanPatent Application No. 10-2013-0060169, filed on May 28, 2013 in theRepublic of Korea, which all of these applications are all herebyincorporated by reference as if fully set forth herein. Notice: Morethan one reissue application has been filed for the reissue of U.S. Pat.No. 9,293,485. The reissue applications are application Ser. Nos.15/825,950 (present application) and 16/999,784 (divisional reissueapplication of the present application) filed on Aug. 21, 2020.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flexible display device and a methodfor manufacturing the same to reduce a width of a peripheral edge area(i.e.., bezel) of a display area.

2. Discussion of the Related Art

As part of the evolution of the information age, the field of displaysto visually display electric information signals is rapidly growing. Inresponse to this trend, a great deal of research to increase performancesuch as slimness, weight reduction and low power consumption of variousflat display devices continues.

Representative examples of flat display devices include liquid crystaldisplays (LCDs), plasma display panels (PDPs), field emission displays(FEDs), electro-luminescent displays (ELDs), electrowetting displays(EWDs), organic light emitting diode (OLEDs) displays and the like.These flat display devices, in common, necessarily include a flatdisplay panel. The flat display panel has a structure in which a pair ofsubstrates is joined via an inherent luminous or polarizing substancewhile facing each other.

Recently, flat display devices may be implemented into flexible displaydevices using flexible substrates made of flexible materials such asplastics to maintain display performance while being bendable likepaper.

Such a flexible display device may be more widely applied thanconventional display devices lacking flexibility, and research anddevelopment into practical applications of flexible display devicescontinues.

Meanwhile, in general, flat display devices including flexible displaydevices include a display area to actually display an image and anon-display area to enable connection to various driving circuits orexterior circuits as a region other than the display area.

In this regard, as a width of a peripheral edge region, that is, abezel, of the display area, increases, the display area appears to theobserver to be smaller, and product values of display devices,associated with aesthetics and usability are lowered.

Therefore, research and development associated with reduction of widthof the non-display area in order to reduce bezel width are made.However, disadvantageously, there is a limitation to reduction of widthin the non-display area due to areas corresponding to pads forconnection to driving circuits or exterior circuits disposed in thenon-display area.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a flexible displaydevice and a method for manufacturing the same that substantiallyobviate one or more problems due to limitations and disadvantages of therelated art.

An object of the present invention is to provide a flexible displaydevice including a bezel having a width narrower than a non-display areausing flexibility of flexible substrates and a method for manufacturingthe same.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein,provided is a flexible display device including a substrate defined by adisplay area and a non-display area being an outer region of the displayarea and including a link area and a pad area, the substrate beingformed of a flexible material, a plurality of gate lines and a pluralityof data lines formed in the display area on the substrate, such that thegate lines and the data lines cross each other to define a plurality ofpixel areas in the display area, a plurality of pads formed in the padarea, each pad being connected to an exterior circuit to supply adriving signal to a signal line selected from the gate line and the dataline, a plurality of links formed in the link area, the links connectingthe respective pads and the signal lines, a plurality of insulationfilms formed over the entire surface of the substrate, the insulationfilms insulating conductive layers from one another, and a first bendinghole formed in a bending area of the non-display area, the first bendinghole passing through at least one of the insulation films disposed underthe link, wherein the bending area is bent such that the pads aredisposed on the lower surface of the substrate.

In accordance with another aspect of the present invention, provided isa method for manufacturing a flexible display device including forming asubstrate defined by a display area and a non-display area being anouter region of the display area and including a link area and a padarea, using a flexible material, forming a buffer film over the entiresurface of the substrate, forming a gate insulation film over the entiresurface of the buffer film, forming gate lines in the display area onthe gate insulation film, forming an interlayer insulation film over theentire surface of the gate insulation film such that the interlayerinsulation film covers the gate lines, forming a first bending holepassing through at least the gate insulation film, and the interlayerinsulation film in a bending area, wherein the bending area bends suchthat the pad area of the non-display area is disposed on the lowersurface of the substrate, forming data lines and a plurality of links,wherein the data lines formed in the display area on the interlayerinsulation film such that the data lines cross the gate lines, andwherein the plurality of links are connected to signal lines selectedfrom the gate lines and the data lines in the linking area on theinterlayer insulation film, forming a protective film over the entiresurface of the interlayer insulation film such that the protective filmcovers the data lines and the links, forming a plurality of padsconnected to the links and connected to an exterior circuit to supply adriving signal to the signal line on the protective film, and bendingthe bending area such that the pads are disposed on the lower surface ofthe substrate.

The flexible display device according to the embodiments of the presentinvention can reduce a width of a bezel without reducing a width of thenon-display area, since the plurality of pads are disposed on the lowersurface of the substrate by bending the bending area. Accordingly, thedisplay devices have improved product values associated with aestheticsand usability.

The flexible display device includes the first bending hole, thusenabling removal of parts of each the buffer film, the gate insulationfilm and the interlayer insulation film which correspond to the bendingarea. As a result, it is possible to prevent problems such asapplication of relatively greater bending stress to the buffer film, thegate insulation film and the interlayer insulation film than bendingstress to the substrate, when the bending area is bent, generation ofcracks and thus breakage (disconnection) of links (wiring). As a result,it is possible to improve reliability and yield of the display device.

In addition, the flexible display device further includes ananti-etching layer between the substrate and the buffer film in a partof the non-display area, that is, in a region including the firstbending hole, thus preventing the substrate from being etched by anetching process to form the first bending hole. As a result, it ispossible to prevent permeation of foreign matter causing defects andthereby improve reliability and yield of the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a flexible display device accordingto the first embodiment of the present invention;

FIG. 2 is a sectional view illustrating a pixel area according to thefirst embodiment of the present invention;

FIG. 3 is a sectional view illustrating a state in which a bending areaof a substrate is bent in the flexible display device of FIG. 1;

FIG. 4 is a plan view illustrating a part I of FIG. 1;

FIG. 5 is a sectional view illustrating a part II-II of FIG. 4;

FIG. 6 is a sectional view illustrating a part of FIG. 4;

FIG. 7 is a plan view illustrating a part I of FIG. 1 according to thesecond embodiment of the present invention in more detail;

FIG. 8 is a sectional view illustrating a part IV-IV′ of FIG. 7;

FIG. 9 is a sectional view illustrating a part II-II′ of FIG. 4according to the third embodiment of the present invention;

FIG. 10 is a plan view illustrating the part I of FIG. 1 according tothe fourth embodiment of the present invention ore detail;

FIG. 11 is a sectional view illustrating a part V-V′ of FIG. 10;

FIG. 12 is a flowchart illustrating a method for manufacturing theflexible display device according to the first embodiment of the presentinvention;

FIG. 13 is a flowchart illustrating formation of a cell array, links andpads;

FIGS. 14a to 14e, 15a to 15g, and 16a and 16b are views illustrating amethod for manufacturing the flexible display device described in FIGS.12 and 13;

FIG. 17 is a flowchart illustrating a method for manufacturing theflexible display device according to the second embodiment of thepresent invention;

FIG. 18 is a flowchart illustrating a method for manufacturing theflexible display device according to the third embodiment of the presentinvention; and

FIG. 19 is a view illustrating a process for forming a pre-bending holein FIG. 18.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a flexible display device and a method for manufacturingthe same according to the present invention will be described in detailwith reference to the annexed drawings.

First, a flexible display device according to a first embodiment of thepresent invention will be described with reference to FIGS. 1 to 6.

FIG. 1 is a plan view illustrating a flexible display device accordingto the first embodiment of the present invention. FIG. 2 is a sectionalview illustrating a pixel area according to the first embodiment of thepresent invention. FIG. 3 is a sectional view illustrating a state inwhich a bending area of a substrate is bent in the flexible displaydevice of FIG. 1. FIG. 4 is a plan view illustrating a part 1 of FIG. 1.FIG. 5 is a sectional view illustrating a part II-II′ of FIG. 4. FIG. 6is a sectional view illustrating a part of FIG. 4.

As shown in FIG. 1, the flexible display device 100 according to thefirst embodiment of the present invention includes: a substrate 101; aplurality of gate lines GLs and a plurality of data lines DLs; aplurality of pads PD; a plurality of links LK; and insulation films 102,103, 104 and 105 (not shown in FIG. 1, but shown in below-described FIG.2).

The substrate 101 is formed of a flexible material. The substrate 101 isdefined by a display area AA and a non-display area NA which is an outerregion of the display area AA. The non-display area NA includes a linkarea LKA and a pad area PDA. The plurality of gate lines GLs and theplurality of data lines DLs are formed in the display area AA on thesubstrate 101, such that the gate lines GLs and the data lines DLsindependently cross each other to define a plurality of pixel areas PAin the display area AA. The plurality of pads PD is formed in the padarea PDA. The plurality of pads PD is connected to exterior circuits tosupply a driving signal to a signal line selected from the gate line GLand the data line DL. The plurality of links LK is formed in the linkarea LKA. The plurality of links LK connects the pads PD and the signallines selected from GLs and DLs. The insulation films 102, 103, 104 and105 are formed over the entire surface of the substrate. The insulationfilms 102, 103, 104 and 105 insulate conductive layers from one another.

The display device 100 further includes a plurality of thin filmtransistors TFTs; and a light emitting array. The plurality of thin filmtransistors TFTs are formed at the intersections between the gate linesGLs and the data lines DLs corresponding to the respective pixel areasPA. The light emitting array includes a plurality of light emittingelements EL formed in the respective pixel areas PA.

For example, as shown in FIG. 2, the flexible display device 100includes the substrate 101 formed of a flexible material, a buffer film102 formed over the entire surface of the substrate 101, and a pluralityof TFTs and a plurality of light emitting elements ELs formed in thedisplay area on the buffer film 102.

The substrate 101 is formed of a plastic or a metal as a flexiblematerial. In case that the substrate 101 is formed of a plastic, aplastic having high heat resistance is selected while taking intoconsideration the fact that the substrate 101 is exposed to a hightemperature atmosphere during deposition and etching processes ofvarious films.

For example, the substrate 101 may be formed of a polymer plasticmaterial such as polyimide (PI), polyethersulforte (PES), polyacrylate(PAR), polyetherimide (PEI), polyethylene naphthalate (PET), andpolyethylene terephthalate (PET). Alternatively, the substrate 101 maybe formed of a metal such as aluminum o copper.

The buffer film 102 prevents deterioration factors such as moisture oroxygen from permeating into the light emitting element EL through thesubstrate 101. The buffer film 102 has a laminate structure of two ormore insulation films wherein the insulation films are different interms of at least one of thickness, component and compositional ratio.For example, the buffer film 102 may be formed of SiNx or SiOy.

Each thin film transistor TFT includes: an active layer 111; a gateinsulation film 103; a gate electrode 113; an interlayer insulation film104; a source (or drain) electrode 114a; a drain (or source) electrode114b; and a protective film 105.

The active layer 111 is formed in a part of each pixel area PA on thebuffer film 102. The active layer 111 forms a channel based on a gatevoltage of the gate electrode. The active layer 111 includes a channelarea 111a, a source region 111b, and drain region 111c. The channel area111a overlaps at least a part of the gate electrode 113 on the gateinsulation film 103 to form a channel according to a voltage level ofthe gate electrode 113. The source region 111b and the drain region 111care disposed at both sides of the channel area 111a.

The gate insulation film 103 is formed over the entire surface of thebuffer film 102 such that the gate insulation film 103 covers the activelayer 111. The gate electrode 113 is formed on the gate insulation film103 such that at least a part of the gate electrode 113 overlaps thechannel area 111a of the active layer 111. The gate electrode 113 isconnected with the data line DL. The interlayer insulation film 104 isformed on the gate insulation film 103 such that the interlayerinsulation film 104 covers the gate electrode 113.

The source electrode 114a is formed on the interlayer insulation film104 such that the source electrode 114a overlaps the source region 111b.The source electrode 114a is connected to the data line DL. In addition,the source electrode 114a is also connected to a source region 111bthrough a source hole SH which passes through the gate insulation film103 and the interlayer insulation film 104 to expose at least a part ofthe source region 111b.

Similarly, the drain electrode 114b is formed on the interlayerinsulation film 104 such that the drain electrode 114b overlaps thedrain region 111c. The drain electrode 114b is connected to the lightemitting element EL in each pixel area PA. In addition, the drainelectrode 114b is also connected to a drain region 111c through a drainhole DH which passes through the gate insulation film 103 and theinterlayer insulation film 104 to expose at least a part of the drainregion 111c.

The protective film 105 is formed on the interlayer insulation film 104such that the protective film 105 covers the source electrode 114a andthe drain electrode 114b. Furthermore, although not illustrated in FIG.2, the gate line (GL of FIG. 1) is formed together with the gateelectrode 113 on the gate insulation film 103.

In addition, the data line (DL of FIG. 1, not shown in FIG. 2) is formedon the interlayer insulation film 104 together with the source electrode114a and the drain electrode 114b.

Each light emitting element (EL) includes: a first electrode 121; a bank122; a light emitting layer 123; and a second electrode 124. The firstelectrode 121 is formed in each pixel area PA on the protective film105. The bank 122 is formed on a periphery of each pixel area PA on theprotective film 105 to overlap at least a part of the edge of the firstelectrode 121. The light emitting layer 123 is formed on the firstelectrode 121. The second electrode 124 is formed on the entire surfacesof the light emitting layer 123 and the bank 122 such that the secondelectrode 124 faces the first electrode 121 via the light emitting layer123.

The first electrode 121 is connected to the drain electrode 114b througha contact hole CH that passes through the protective film 105 to exposeat least a part of the drain electrode 114b.

The light emitting layer 123 between the first electrode 121 and thesecond electrode 124 emits light based on current applied from the thinfilm transistor TFT.

The flexible display device 100 further includes a sealing layer 130.The sealing layer 130 faces the substrate 101 via the light emittingarray including the light emitting elements ELs in the display area AA.The sealing layer 130 seals the light emitting array. The sealing layer130 prevents permeation of deterioration factors such as oxygen ormoisture into the light emitting elements EL.

Description will be given with reference to FIG. 1 again.

Although not described in detail in FIG. 1, in general, an upper surfaceof the substrate 101 has a rectangular shape having four sides. When thedisplay area AA is disposed in the center of the upper surface of thesubstrate 101, the non-display area NA includes four side areas parallelto one another at different sides of the substrate 101. However, thisdisposition is provided only as an example, and it is clear that thenon-display area NA may include one or more side areas according to theshape of the substrate 101, shape of the display area AA and position ofthe display area AA in the substrate 101.

As shown in FIG. 1, a side area (NA1, corresponding to a right side ofthe outer region of the display area AA in FIG. 1) of the non-displayarea NA includes a pad area PDA provided with pads PD, and a link areaLKA which is interposed between the pad area PDA and the display area AAand is provided with a plurality of links LK. In addition, a portion ofthe side area NA1 parallel to one side of the substrate 101 correspondsto a bending area which is bent such that the pad PD is disposed on thelower surface of the substrate 101.

in FIG. 1, among the non-display area NA, only the right side area NA1,where the pad PD corresponding to the gate line CT is disposed, includesthe bending area BA. However, this disposition is provided as an exampleand each side area of the non-display area NA includes a bending areaBA. That is, among the non-display area NA, a side area (correspondingto the non-display area NA disposed in an upper side of display area AAin FIG. 1), where the pad PD corresponding to the data line DL isdisposed, also includes a bending area BA such that the pad PD connectedto the data line DL is disposed on the lower surface of the substrate101.

Here, at least a part of the link area LKA becomes the bending area BA,therefore a part of each link LK is disposed on the bending area BA. InFIG. 1, a part of the link area LKA is the bending area BA. Thisconfiguration is provided only as an example and the bending area BA maybe wider than the link area LKA.

Specifically, as shown in FIG. 3, the bending area BA of the substrate101 is bent to enable the pad of the pad area PDA (PD of FIG. 1) to bedisposed on the lower surface of the substrate 101.

An insulating material, in particular, an inorganic insulating materialmay be used to form at least one of the buffer film 102, the gateinsulation film 103 and the interlayer insulation film 104. They are ingeneral harder than the flexible material which is used to form thesubstrate 101. Therefore, when the substrate 101 bends in the bendingarea BA on condition that the insulating material is disposed in thebending area BA, bending stress is applied to the insulating material.For this reason, cracks may develop in the insulating material. Thecracks of the insulating material also have an effect on the link LK,thus disadvantageously causing defects such as breakage (disconnection)of the link LK.

In order to prevent breakage (disconnection) defects caused by bendingstress, the amount of the insulating material disposed in the bendingarea BA should be minimized.

Thus, the flexible display device according to the first embodiment ofthe present invention further includes a first bending hole disposed inthe bending area BA.

As shown in FIGS. 4 and 5, the flexible display device 100 furtherincludes: an anti-etching layer 106; and a first bending hole BH1. Theanti-etching layer 106 forms in at least one side area NM of thenon-display area NA on the substrate 101. The first bending hole BH1 isformed in the bending area BA, wherein the first bending hole BH1 passesthrough at least one insulation film disposed under the link LK among aplurality of insulation films including a buffer film 102, a gateinsulation film 103, an interlayer insulation film 104 and a protectivefilm 105.

The first bending hole BH1 is formed to expose at least a part of theanti-etching layer 106. Each link LK disposed on the interlayerinsulation film 104 directly contacts at least a part of theanti-etching layer 106 exposed through the first bending hole BH1.

The anti-etching layer 106 functions to prevent exposure of thesubstrate 101 during etching of the buffer film 102, the gate insulationfilm 103 and the interlayer insulation film 104 to form the firstbending hole BH1.

That is, when the buffer film 102, the gate insulation film 103 and theinterlayer insulation film 104 are inorganic insulating materials, dryetching is generally used to form the first bending hole BH1 passingthrough the buffer film 102, the gate insulation film 103 and theinterlayer insulation film 104. In this case, when the substrate 101 isa plastic material, the first bending hole BH1 is formed underover-etching conditions and is then exposed to dry etching. For thisreason, the substrate 101 is also etched, thus causing generation offoreign matter. This foreign matter causes defects, such as breakage(disconnection) or short circuit, and damage to the light emitting layer(123 of FIG. 2), thus deteriorating reliability and yield of theflexible display device 100.

Thus, according to the first embodiment of the present invention, theflexible display device 100 includes the anti-etching layer 106 as anetch stopper to prevent exposure of the substrate 101 during etchingprocess for formation of the first bending hole BH1, and theanti-etching layer 106 is disposed between the substrate 101 and aplurality of insulating layers 102, 103, 104 and 105 in the side areaNA1 including the bending area BA where the first bending hole BH1 is tobe formed.

As a result, the anti-etching layer 106 prevents the substrate 101 frombeing etched together with the buffer film 102, the gate insulation film103 and the interlayer insulation film 104 during formation of the firstbending hole BH1. For this reason, introduction of foreign matter isprevented, and reliability and yield of the flexible display device 100are thus improved.

Such an anti-etching layer 106 may be formed to correspond to only theside area NA1 including the bending area BA, or to correspond to theentire region of the non-display area NA, regardless of presence of thebending area BA.

In addition, like the source electrode (114a of FIG. 2) and the drainelectrode (114b of FIG. 2), links LK are formed on the interlayerinsulation film 104.

As described above, the gate line GL is formed on the gate insulationfilm 103 together with the gate electrode (113 of FIG. 2). The link LKcorresponding to the gate line GL is connected to the gate line GLthrough the link hole LKH which passes through the interlayer insulationfilm 104 to expose at least a part of the gate line GL.

In addition, the data line (DL of FIG. 1) is formed on the interlayerinsulation film 104. In this case, an additional contact hole to connectthe data line DL to the link LK is unnecessary. That is, the link LKcorresponding to the data line DL may extend from the data line DL.

The protective film 105 is formed over the entire surface of theinterlayer insulation film 104 such that the protective film 105 coversthe source electrode 114a and the drain electrode 114b, the firstbending hole BH1 and the links LK.

The pads PD are formed on the protective film 105 and are connected tothe respective links LK through the pad holes PDHs which passes throughthe protective film 105 to expose at least a part of the link LK.

Meanwhile, at least a part of the anti-etching layer 106 is benttogether with the bending area BA of the substrate 101, therefore amaterial for the anti-etching layer 106 is softer than the inorganicinsulating material selected as a material for the buffer film 102, thegate insulation film 103 and the interlayer insulation film 104. Inaddition, upon formation of the first bending hole BH1, so as tominimize etching of the anti-etching layer 106 together with the gateinsulation film 103 and the interlayer insulation film 104, the materialfor the anti-etching layer 106 preferably has an etch ratio lower thanthe gate insulation film 103 and the interlayer insulation film 104.

The material for the anti-etching layer 106 satisfying these conditionsmay be an insulating material such as amorphous silicon (a-Si).Alternatively, the material may be a conductive metal material such asITO, Mo or Ti, which is advantageous in terms of process cost, easinessand universality.

Furthermore, the links LK contact at least a part of the anti-etchinglayer 106 exposed through the first bending hole BH1. For this reason,the links LK are disadvantageously short-circuited through theanti-etching layer 106, when the anti-etching layer 106 is formed of aconductive material and is provided as a single pattern.

As shown in FIGS. 4 and 6, the anti-etching layer 106 includes aplurality of anti-etching, patterns 106a and 106b corresponding to therespective links LK. Here, the anti-etching patterns 106a and 106b areprovided as independent patterns that are not connected to each other toprevent the links LK from being connected to one another by theanti-etching layer 106.

When the anti-etching layer 106 is provided as the anti-etching patterns106a and 106b, the first bending hole BH1 may include a plurality offirst bending holes such that the first bending holes expose at least apart of each of the anti-etching patterns 106a and 106b. That is, theflexible display device 100 includes the plurality of the first bendingholes Bill corresponding to the plurality of the anti-etching patterns106a and 106b.

The links LK are formed such that the links ILK one-on-one contact theanti-etching patterns 106a and 106b at least a part of each of which isexposed through the first bending holes Bill. As a result, it ispossible to prevent short circuit between the links LK caused by theanti-etching layer 106.

As described above, the flexible display device 100 according to thefirst embodiment of the present invention includes a first bending holeBH1. The first bending hole is formed by removing the buffer film 102,the gate insulation film 103 and the interlayer insulation film 104 toexpose the anti-etching layer 106 in the bending area BA. As a result,it is possible to prevent breakage (disconnection) defects of the linkLK caused by diffusion of cracks which may develop in the inorganicinsulating material due to application of bending stress, wherein theinorganic insulating material is used to form the buffer film 102, thegate insulation film 103 and the interlayer insulation film 104.

The flexible display device 100 further includes the anti-etching layer106. The anti-etching layer 106 is disposed between the substrate 101and the buffer film 102 in a region Where the first bending hole BH1 isformed and the neighboring region thereof. Materials used for theanti-etching layer 106 may have lower etching rates than materials usedfor the buffer film 102, the gate insulation film 103 and the interlayerinsulation film 104. Consequently, the anti-etching layer 106 enables toprevent etching of the substrate 101, in a case in which etching forformation of the first bending hole BH1 is continuously performed underover-etching conditions even after removal of the buffer film 102, thegate insulation film 103 and the interlayer insulation film 104. As aresult, it is possible to prevent generation of foreign matter caused byunsuitable etching of the substrate 101, thus preventing defects causedby the foreign matter and improving reliability and yield.

Next, the flexible display device according to the second embodiment ofthe present invention will be described with reference to FIGS. 7 and 8.

FIG. 7 is a plan view illustrating the part I of FIG. 1 according to thesecond embodiment of the present invention in more detail. FIG. 8 is asectional view illustrating the part IV-IV′ of FIG. 7.

As shown in FIGS. 7 and 8, the flexible display device according to thesecond embodiment further includes at least one second bending hole BH2.The second bending hole BH2 is formed in the periphery of the link LK ineach first bending hole BH1. The other portions are the same as theflexible display device of the first embodiment shown in FIGS. 1 to 6.An overlapping description thereof is thus omitted below.

Each second bending hole Bin shown in FIGS. 7 and 8 is used for removalof bending stress factors, that is, the protective film 105 and theanti-etching layer 106 left in the periphery of the link LK in the firstbending hole BH1. In other words, each second bending hole BH2 passesthrough the protective film 106 105 and the anti-etching layer 106 inthe periphery of the link LK in the first bending hole BH1 to expose apart of the substrate 101.

As a result, when the protective film 105 and the anti-etching layer 106are removed by formation of the second bending hole BH2 in a portion ofthe bending area BA, excluding the periphery of the link LK, bendingstress factors are further reduced and defects caused by bending stresscan thus be further prevented.

Next, the third embodiment of the present invention will be describedwith reference to FIG. 9.

FIG. 9 is a sectional view illustrating the part IMF of FIG. 4 accordingto the third embodiment of the present invention.

As shown in FIG. 9, the flexible display device according to the thirdembodiment further includes a pre-bending hole pre_BH1. The pre-bendinghole pre_BH1 is formed after formation of the buffer film 102 and beforeformation of the active layer 111 to correspond to the bending area BAand to pass through the buffer film 102 in a width greater than thefirst bending hole BH1. The other portions are the same as that of thefirst or second embodiment. An overlapping description thereof is thusomitted below.

Forming the pre-bending hole pre_BH1 shown in FIG. 9 results in removingthe buffer film 102 in the bending area prior to the formation of thefirst bending hole BH1. Accordingly, it is not necessary to remove thebuffer film 102 anymore in forming the first bending hole BH1, but toremove only the gate insulation film 103 and the interlayer insulationfilm 104. Meanwhile, the source hole SH and the drain hole DH passthrough the gate insulation film 103 and the interlayer insulation film104, like the first bending hole BH1 of the present embodiment. Damageto the active layer 111 exposed due to the formation of the source holeSH and the drain hole DH caused by over-etching during the formation ofthe first bending hole BH1 can thus be minimized.

Next, the flexible display device according to the fourth embodiment ofthe present invention will be described with reference to FIGS. 10 and11.

FIG. 10 is a plan view illustrating the part I of FIG. 1 according tothe fourth embodiment of the present invention in more detail. FIG. 11is a sectional view illustrating the part V-V′ of FIG. 10.

As shown in FIGS. 10 and 11, the flexible display device of the fourthembodiment is configured to form the first bending hole BH1 and theanti-etching layer 106 further in the pad area PDA as well as thebending area BA. The other portions are the same as those of the firstto third embodiments. An overlapping description thereof is thus omittedbelow.

Next, a method for manufacturing the flexible display device accordingto the first embodiment of the present invention will be described withreference to FIGS. 12, 13, 14a to 14c, 15a to 15g, and 16a and 16b.

FIG. 12 is a flowchart illustrating a method for manufacturing theflexible display device according to the first embodiment of the presentinvention. As shown in FIG. 12, the method for manufacturing theflexible display device according to the first embodiment includes:preparing, at step S110, a substrate 101 formed of a flexible materialand including a display area AA and a non-display area NA1 which is anouter region of the display area AA and includes a link area LKA and apad area PDA; forming, at step S120, an anti-etching layer 106 in atleast a part of the non-display area NA1 on the substrate 101; forming,at step S130, a buffer film 102 over the entire surface of the substrate101.

The method further includes: forming, at step S140, (1) gate lines GLand data lines DL on the buffer film 102 in the display area AA; (2) aplurality of insulation films on the entire surface of the buffer film102; (3) a first bending hole BH1 in the bending area BA of thenon-display area NA1; (4) a plurality of pads PD in the pad area FDA ofthe nondisplay area NA1; and (5) a plurality of links LK in the linkarea of the non-display area NA1,

At the above step S140, the first bending hole is configured to passesthrough at least one of a plurality of insulation films in the bendingarea of the non-display area. The bending area is configured to be bentsuch that the pad area is disposed on the lower surface of thesubstrate. The plurality of pads is configured to be connected to anexterior circuit to supply a driving signal to any one signal line ofthe gate line and the data line. The plurality of links is configured toconnect respective pads with the signal lines.

The method further includes: forming, at step S150, a light emittingarray including a plurality of light emitting elements EL in respectivepixel areas PA; forming, at step S160, a sealing layer 130 in thedisplay area AA. The sealing layer 130 seals the light emitting elementsEL such that the sealing layer 130 faces the substrate 101 via the lightemitting elements EL; and bending, at step S170, a bending area BA suchthat the pads PD are disposed on the lower surface of the substrate 101.

FIG. 13 is a flowchart illustrating formation of a cell array, links andpads, as shown in FIG. 13, formation of the gate lines GL and the datalines DL, the insulation films, the first bending hole BH1, the pads PDand the links LK executed at step S140 includes: (1) forming, at stepS141, an active layer 111 in a part of each pixel area PA on the bufferfilm 102; (2) forming, at step S142, a gate insulation film 103 over theentire surface of the buffer film 102; (3) forming, at step S143, gatelines GL and gate electrodes 113 connected thereto on the gateinsulation film 103; (4) forming, at step S144, an interlayer insulationfilm 104 over the entire surface of the gate insulation film 103; (5)forming, at step S145, a source hole SH, a drain hole DH, a link holeLKH and the first bending hole BH1, wherein each of the source hole, thedrain hole and the link hole passes through the interlayer insulationfilm 104 and the gate insulation film 103, and wherein the first bendinghole BH1 passes through the interlayer insulation film 104, the gateinsulation film 103 and the buffer film 102; (6) forming, at step S146,the data lines DL, the source electrode 114a, the drain electrode 114band the links LK on the interlayer insulation film 104; (7) forming, atstep S147, a protective film 105 over the entire surface of theinterlayer insulation film 104; (8) forming, at step S148, a pad holePDH passing through the protective film 105; and (9) forming at stepS149, the pads PD on the protective film 105.

FIG. 14a illustrates a first process of a method for manufacturing theflexible display device. As shown in FIG. 14a, a substrate 101 formed ofa flexible material is prepared (S110). For this purpose, a sacrificialsubstrate (not shown) may be used.

FIG. 14b illustrates a second process of a method for manufacturing theflexible display device. As shown in FIG. 14b, an anti-etching layer 106is formed in at least a part of the non-display area NA including thebending area BA on the substrate 101 (S120).

The anti-etching layer 106 may be formed in the entirety of thenon-display area NA, or only in at least one of selected side area ofthe non-display area NA, including the later-formed first bending hole(Bill of FIGS. 4 to 6).

The anti-etching layer 106 includes the bending area BA and is thus benttogether with the substrate 101. Although the etching process to formthe first bending hole BH1 is performed under over-etching conditions,it is necessary to prevent exposure of the substrate during etching andgeneration of foreign matter caused by the anti-etching layer 106.Accordingly, a material for the anti-etching layer 106 may be selectedfrom materials having a higher softness in other words, lower hardness)and a lower etch ratio than each of inorganic insulating materials forat least one of the later-formed buffer film 102, gate insulation film103 and interlayer insulation film 104.

For example, a material for the anti-etching layer 106 is selected fromITO, Mo, Ti and a-Si which are advantageous in terms of process cost,easiness and universality.

Furthermore, because the plurality of links (LK of FIGS. 1 and 5)connected to the anti-etching layer 106 through the first bending holeBH1, in a case in which the anti-etching layer 106 is formed of aconductive material, the links LK may be short-circuited through theanti-etching layer 106. To prevent this, the anti-etching layer 106 isprovided as a plurality of anti-etching patterns (106a and 106b of FIGS.4, 6-8 and 10) that correspond to a plurality of links LK and areseparated from one another.

FIG. 14c illustrates a third process of a method for manufacturing theflexible display device. As shown in FIG. 14c, a buffer film 102 isformed over the entire surface of the substrate 101 (S130).

FIG. 15a illustrates a fourth process of a method for manufacturing theflexible display device. As shown in FIG. 15a, the active layer 111 isformed on the buffer film 102 (S141), and a gate insulation film 103covering the active layer 111 is formed over the entire surface of thebuffer film 102 (S142). The active layer 111 includes a channel area111a, and a source region 111b and a drain region 111c disposed at bothsides of the channel area 111a.

Then, a gate electrode 113 overlapping at least a part of a channel areaof the active layer 111 and gate lines (not shown, but corresponding toGL of FIGS. 1 and 5) electrically connected to the gate electrode 113are formed on the gate insulation film 103 (S143). Next, the interlayerinsulation film 104 covering the gate electrode 113 and the gate linesGL is formed over the entire surface of the gate insulation film 103(S144).

FIGS. 15b and 15c illustrate fifth and sixth processes of a method formanufacturing the flexible display device. As shown in FIG. 15b, theinterlayer insulation film 104 and the gate insulation film 103 areselectively patterned to form a source hole SH, a drain hole DH.Similarly, as shown in FIG. 15c, the interlayer insulation film 104, thegate insulation film 103 and the buffer film 102 are selectivelypatterned to form a source hole SH, a drain hole DH, a link hole LKH anda first bending hole BH1 (S145).

The source hole SH passes through the interlayer insulation film 104 andthe gate insulation film 103 to expose at least a part of the sourceregion 111b.

The drain hole DH passes through the interlayer insulation film 104 andthe gate insulation film 103 to expose at least a part of the drainregion 111c.

The link hole LKH functions as a contact hole to connect the gate lineGL and the links LK disposed in a layer different from the gate line GLand passes through the interlayer insulation film 104 and the gateinsulation film 103 to expose at least a part of the gate line GL.

The first bending hole BH1 functions to prevent generation of crackscaused by application of greater bending stress to the buffer film 102,the gate insulation film 103 and the interlayer insulation film 104, ascompared to stress applied to the substrate 101, when the bending areaBA is bent. The first bending hole BH1 passes through the buffer film102, the gate insulation film 103 and the interlayer insulation film104, and exposes at least a part of the anti-etching layer 106 in thebending area BA.

FIGS. 15b and 15c illustrate seventh and eighth processes of a methodfur manufacturing the flexible display device. As shown in FIGS. 15d and15e, the source electrode 114a, the drain electrode 114b, the data line(DL of FIG. 1), and the links LK are formed on the interlayer insulationfilm 104. The data line DI, is connected to one of the source electrodeand the drain electrode. Each of the links LK is connected to one of thegate lines GL and the data lines DL. The links LK are formed to beextended to the pad area PDA.

The source electrode 114a is connected to the source region 111b of theactive layer 111 through the source hole SH, and the drain electrode114b is connected to the drain region 111c of the active layer 111through the drain hole DH.

Some links LK corresponding to the gate lines GL are connected to thegate line GL, through the link hole LKH, and other links LKcorresponding to the data lines DL are configured to be extended fromthe data line DL.

In addition, the links LK directly contact the anti-etching layer 106through the first bending hole BH1 in the bending area BA.

When the anti-etching layer 106 is a conductive material, the links LKcontact a plurality of anti-etching patterns (corresponding to 106a and106b of FIG. 3) one-on-one through the first bending holes BH1.

FIG. 15f illustrates a ninth process of a method for manufacturing theflexible display device. As shown in FIG. 15f, a protective film 105covering the source electrode 114a, the drain electrode 114b, data linesDL, links LK and the first bending hole BH1 is formed over the entiresurface of the interlayer insulation film 104 (S147).

FIG. 15g illustrates a tenth process of a method for manufacturing theflexible display device. As shown in FIG. 15g, a pad hole PDH passingthrough the protective film 105 to expose at least a part of the link LKis formed in at least a part of the pad area PDA (S148) and a pluralityof pads PD connected to a plurality of links LK one-on-one are formed onthe protective film 105 (S149).

FIG. 16a illustrates an eleventh process of a method for manufacturingthe flexible display device. As shown in FIG. 16a, a plurality of lightemitting elements ELs is formed on the protective film 105. each of theplurality of light emitting elements ELs includes a first electrode 121,a bank 122, a light emitting layer 123 and a second electrode 124. Theplurality of light emitting elements is configured to form a lightemitting array corresponding to the display area (S150).

FIG. 16b illustrates a twelfth process of a method for manufacturing theflexible display device. As shown in FIG. 16b, a sealing layer 130 isformed in the display area AA to face the substrate 101 via the lightemitting element EL. The sealing layer is formed to seal the lightemitting element EL (S160).

Although not illustrated, a method for the flexible display deviceaccording to the fourth embodiment of the present invention(corresponding to FIGS. 10 and 11) is the same as in FIG. 14b, exceptthat, during formation of the anti-etching layer 106 (S120), theanti-etching layer 106 is further formed in the pad area PDA as well asthe bending area BA. In addition, the method for manufacturing theflexible display device according to the fourth embodiment is the sameas in FIG. 15c, except that, during formation of the source hole SH, thedrain hole DH, the link hole LKH and the first bending hole BH1 (S145),the first bending hole BH1 is further formed in the pad area PDA as wellas in the bending area BA and an overlapping description thereof is thusomitted below.

As shown in FIG. 3, the bending area BA is bent and the pads PD aredisposed on the lower surface of the substrate 101 (S170).

Meanwhile, although not illustrated in FIG. 12, FIGS. 14a to 14c, FIGS.15a to 15g, and FIGS. 16a and 16b in detail, a sacrificial substrate(not shown) may be used during preparation of the substrate 101 (S110).That is, the preparation of the substrate 101 may be carried out bylaminating a flexible material on the sacrificial substrate (not shown).In this case, the method for manufacturing the flexible display devicefurther includes removing the sacrificial substrate (not shown) afterformation of the sealing layer 130 (S160), and before bending thebending area BA of the substrate 101 (S170).

A method for manufacturing the flexible display device according to thesecond embodiment will be described with reference to FIG. 17.

FIG. 17 is a flowchart illustrating the method for manufacturing theflexible display device according to the second embodiment.

As shown in FIG. 17, the method for manufacturing the flexible displaydevice according to the second embodiment further forms at least onesecond bending hole BH2 during formation of the pad hole (S148′). Theother portions are the same as the first embodiment described above Anoverlapping description thereof is thus omitted below.

Referring to FIGS. 7 and 8, the second bending hole BH2 passes throughthe protective film 105 and the anti-etching layer 106, and exposes apart of the substrate 101 in the periphery of the link LK in the firstbending hole BM.

The further addition of the second bending hole BH2 enables furtherremoval of the protective film 105 and the anti-etching layer 106disposed in the periphery of the link LK in the bending area BA, furtherreduction of the bending stress factor and improvement in reliabilityand yield of the flexible display device.

Next, referring to FIGS. 18 and 19, a method for manufacturing theflexible display device according to the third embodiment of the presentinvention and the flexible display device manufactured by the methodwill be described.

FIG. 18 is a flowchart illustrating a method for manufacturing theflexible display device according to the third embodiment of the presentinvention. FIG. 19 is a view illustrating a process for forming thepre-bending hole of FIG. 18.

As shown in FIG. 18, the method for manufacturing the flexible displaydevice according to the third embodiment of the present inventionfurther includes forming the pre-bending hole (pre_BH1) before formationof the active layer (S1400). The other portions are the same as thefirst embodiment described above. An overlapping description thereof isthus omitted below.

As shown in FIG. 19, after formation of the buffer layer 102 (S130 ofFIG. 12) and before formation of the active layer 111 (S141), apre-bending hole pre_BH1 is formed in the bending area BA (S1400). Thepre-bending hole pre_BH1 is configured to pass through the buffer layer102 such that the pre-bending hole pre_BH1 exposes at least a part ofthe anti-etching layer 106 (S1400).

When the method further includes the pre-bending hole pre_BH1 (S1400),at the step of forming of the source hole SH, the drain hole DH, thelink hole LKH and the first bending hole BH1 (S145), the etching of thebuffer film 102 which has been carried out only for formation of thefirst bending hole BH1 becomes unnecessary, consequently, it is possibleto prevent the source hole SH, the drain hole DH, and the link hole LKHfrom being excessively etched while the buffer film 102 is completelypatterned to form the first bending hole BH1. As a result, it ispossible to reduce damage to the source region 111b, the drain region111c and the gate line GL by the source hole SH, the drain hole DH andthe link hole LKH, respectively.

The flexible display device according to the embodiments of the presentinvention can reduce a width of a bezel without reducing a width of thenon-display area, since the plurality of pads are disposed on the lowersurface of the substrate by bending the bending area. Accordingly, thedisplay devices have improved product values associated with aestheticsand usability.

The flexible display device includes the first bending hole, thusenabling removal of parts of each the buffer film, the gate insulationfilm and the interlayer insulation film which correspond to the bendingarea. As a result, it is possible to prevent problems such asapplication of relatively greater bending stress to the buffer film, thegate insulation film and the interlayer sulation film than bendingstress to the substrate, when the bending area is bent, generation ofcracks and thus breakage (disconnection) of links (wiring). As a result,it is possible to improve reliability and yield of the display device.

In addition, the flexible display device fluffier includes ananti-etching layer between the substrate and the buffer film in a partof the non-display area, that is, in a region including the firstbending hole, thus preventing the substrate from being etched by anetching process to form the first bending hole. As a result, it ispossible to prevent permeation of foreign matter causing defects andthereby improve reliability and yield of the display device.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for manufacturing a flexible displaydevice comprising: forming a substrate defined by a display area and anon-display area being an outer region of the display area and includinga link area and a pad area, using a flexible material; forming ananti-etching layer in at least a part including the bending area of thenon-display area on the substrate; forming a buffer film over thesurface of the substrate in which the anti-etching layer is formed;forming a gate insulation film over the surface of the buffer film;forming gate lines in the display area on the gate insulation film;forming an interlayer insulation film over the entire surface of thegate insulation film such that the interlayer insulation film covers thegate lines; forming a first bending hole exposing at least a part of theanti-etching layer, the first bending hole passing through at least oneof the buffer film, the gate insulation film and the interlayerinsulation film in a bending area, wherein the bending area bends suchthat the pad area of the non-display area is disposed on the lowersurface of the substrate; forming data lines and a plurality of links,wherein the data lines are formed in the display area on the interlayerinsulation film such that the data lines cross the gate lines, and;forming a plurality of links, wherein the plurality of links areconnected to signal lines selected from the gate lines and the datalines in the linking area on the interlayer insulation film; forming aprotective film over the surface of the interlayer insulation film suchthat the protective film covers the data lines and the links; forming aplurality of pads connected to the links and connected to an exteriorcircuit to supply a driving signal to the signal line on the protectivefilm; and bending the bending area such that the pads are disposed onthe back side of the surface of the substrate, wherein each of the linksincludes a portion overlapping with the first bending hole in thebending area, and wherein each of the links directly contacts at least apart of the anti-etching layer exposed through the first bending hole inthe bending area.
 2. The method according to claim 1, furthercomprising: forming an anti-etching layer in at least a part includingthe bending area of the non-display area on the substrate, beforeformation of the buffer film, wherein the first bending hole furtherpasses through the buffer film to expose at least a part of theanti-etching layer, during formation of the first bending hole, and thelink directly contacts at least a part of the anti-etching layer exposedthrough the first bending hole in the bending area, during formation ofthe link.
 3. The method according to claim 2 1, further comprisingforming at least one second bending hole passing through the protectivefilm and the anti-etching layer in the periphery of the link in thefirst bending hole to expose a part of the substrate, after formation ofthe protective film.
 4. The method according to claim 2 1, wherein theanti-etching layer is further formed in the pad area during formation ofthe anti-etching layer, and the first bending hole is further formed inthe pad area during formation of the first bending hole.
 5. The methodaccording to claim 2 1, wherein, during formation of the anti-etchinglayer, the anti-etching layer is formed using a material having softnesshigher than the insulation films and having an etch ratio lower than theinsulation films upon etching to form the first bending hole.
 6. Themethod according to claim 2 1, wherein, during formation of theanti-etching layer, the anti-etching layer is formed using at least oneof ITO, Mo, Ti, Cu, Ag, Au and a-Si.
 7. The method according to claim 21, wherein the anti-etching layer includes a plurality of anti-etchingpatterns corresponding to the links, during formation of theanti-etching layer, and the first bending hole includes a plurality offirst bending holes to expose at least a part of the respectiveanti-etching patterns during formation of the first bending hole, andthe links contact the anti-etching patterns exposed through the firstbending holes, respectively, during formation of the data lines and thelinks.
 8. The method according to claim 1, further comprising: formingan anti-etching layer in the bending area of the non-display area on thesubstrate, before formation of the buffer film; and forming apre-bending hole passing through the buffer film in the bending areasuch that the pre-bending hole exposes at least a part of theanti-etching layer, after formation of the buffer film., wherein thefirst bending hole passes through the gate insulation film and theinterlayer insulation film in the pre-bending hole, in a width smallerthan the pre-bending hole to expose the anti-etching layer, duringformation of the first bending hole, and the linkeach of the linksdirectly contacts at least a part of the anti-etching layer exposedthrough the pre-bending hole and the first bending hole in the bendingarea, during formation of the link.
 9. The method according to claim 1,wherein a length of the first bending hole in a width direction of thelink is larger than a width of the link.